CN102176004B - Laser time-of-flight measurement device based on multi-channel time delay estimation and method thereof - Google Patents

Laser time-of-flight measurement device based on multi-channel time delay estimation and method thereof Download PDF

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CN102176004B
CN102176004B CN 201110042431 CN201110042431A CN102176004B CN 102176004 B CN102176004 B CN 102176004B CN 201110042431 CN201110042431 CN 201110042431 CN 201110042431 A CN201110042431 A CN 201110042431A CN 102176004 B CN102176004 B CN 102176004B
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陈钱
顾国华
徐伟
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Nanjing University of Science and Technology
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Abstract

The invention discloses a laser time-of-flight measurement device based on multi-channel time delay estimation and a method thereof. The method comprises the following steps: firstly, opening a multi-channel reference channel and a receiving channel immediately when a laser emitter emits a laser beam; secondarily, performing delay-time processing on the signals by the multi-channel reference channel according to a fixed time interval to form multi-channel reference signals; and finally, transmitting the echo signals of the receiving channel and the multi-channel reference signals to a digital signal processing unit by a digital collection unit to carry out cross-correlation operation, and correcting the obtained different time delay estimation values by linear polynomial fitting to obtain the optimal time delay estimation value. The method and the device are completely digitalized; the device is simple; and the method is effective, has small calculation amount and high stability and can effectively improve the measurement accuracy of the laser time-of-flight.

Description

Laser flying time measurement device and the method thereof based on the hyperchannel time delay, estimated
Technical field
The invention belongs to the laser radar signal process field, particularly a kind of devices and methods therefor of measuring the laser flying time, be applied to laser ranging, the purposes such as laser imaging radar.
Background technology
The laser flying time measurement technology is widely used in the direct detection of laser application such as laser ranging, laser imaging radar, and the quality of laser flying time resolution is directly connected to the precision of range observation and the sharpness of Range Imaging.
Traditional simulated laser flight time measurement is divided into to be differentiated and two steps of time interval measurement constantly.Constantly differentiating is generally that Laser emission pulse and echo-pulse are first carried out to simple pre-service, as high pass differential, low-pass filtering etc., then pretreated analog passband signal is crossed to high-speed comparator and extracts the digital signal rising edge that laser starts and ends.Method of discrimination is just used analogy method to extract constantly simply constantly, is subject to decay and the interference of atmosphere, solid suspended particle in the process of flight due to laser, and the impact of the reasons such as target surface characteristic variations, constantly differentiate and have very large error.Two kinds of methods are generally used in time interval measurement: the one, and use programmable logic device (PLD) electronics frequency multiplication to obtain clock signal at a high speed to improve measuring accuracy; The 2nd, use professional timing chip.These two kinds of methods respectively have quality, and the former is subject to the restriction of device technological level to be difficult to reach superfast clock frequency, even it is also very high to reach cost; So the latter is subject to the environmental influence such as temperature very large because device inside adopts analogue technique, there is error in the time value recorded under different temperatures.
It is more active research topic of signal process field that time delay is estimated, its basic problem is to utilize the echoed signal received to estimate quickly and accurately between receiver due to the different time delays that cause of signal propagation distance.Usually the delay time estimation method of using has phase method, two spectrometry, correlation method, sef-adapting filter parameter model etc.For the echo of laser radar, its signal is the class gaussian signal, and noise is white Gaussian noise, and signal and noise, noise and noise are uncorrelated mutually, are very beneficial for estimating the laser flying time with Time Delay Estimation Based.Relevant Time Delay Estimation Method is utilized the relatively similarity between echoed signal and reference signal of cross-correlation technique, and the peak value by related function carrys out the mistiming postponed between estimate echo signal and reference signal.But the picking rate of digital collection unit is limited at present, wants to improve the Laser Time measuring accuracy, only by Time Delay Estimation Based or inadequate.So, be necessary said method is improved.
Summary of the invention
Goal of the invention of the present invention is to improve the measuring accuracy of laser flying time, a kind of laser flying time measurement device and method thereof of estimating based on the hyperchannel time delay is provided, and device is simple, and calculated amount is little, realize simply, can effectively reach and reduce error and put forward high-precision purpose.
Realize that purpose technical scheme of the present invention is: a kind of laser flying time measurement device of estimating based on the hyperchannel time delay, comprise optical system and electronic system two parts, wherein optical system is by transmitting optics, receive optics, the first level crossing and the second level crossing form, electronic system is by generating laser, receive channel, the hyperchannel reference channel, digital collection unit and digital signal processing unit form, the first level crossing is identical with the optical parametric of the second level crossing, before the first level crossing is placed in generating laser, with generating laser angle at 45 °, before the second level crossing is placed in the hyperchannel reference channel, with hyperchannel reference channel angle at 45 °, the first level crossing becomes 90 ° of angles with the second level crossing, before transmitting optics is placed in the first level crossing, before reception optics is placed in receive channel, transmitting optics and reception optics parallel, the generating laser Emission Lasers, one road first sees through the first level crossing, then through transmitting optics, collimate, arrive receive channel through receiving optical convergence after being reflected by target, another Lu Xianjing first flat mirror reflects, enter the hyperchannel reference channel by the second flat mirror reflects, receive channel all is connected with the digital collection unit with the hyperchannel reference channel, this digital collection unit one end is connected with the hyperchannel reference channel with receive channel, the reference analog signal of the analogue echoes signal of receive channel and hyperchannel reference channel is carried out to analog to digital conversion binary coding, the other end is connected with digital signal processing unit, the echo digital signal and the hyperchannel reference digital signal that collect are sent into to digital signal processing unit, digital signal processing unit carries out the line linearity fitting of a polynomial correction of estimating to go forward side by side of simple crosscorrelation time delay by the echo digital signal that receives and hyperchannel reference digital signal and tries to achieve the optimum delay estimated value.
A kind of laser flying Method Of Time Measurement of estimating based on the hyperchannel time delay comprises the following steps:
A, in the moment of Laser emission, open two channels, reference analog signal and analogue echoes signal that two channels receive are designated as respectively x simultaneously 1and x (t) 2(t);
The delay unit of b, hyperchannel reference channel inside to reference analog signal carry out respectively 0, time delay, form N hyperchannel reference signal comprising former reference analog signal, be designated as respectively x 11(t), x 12(t) ... x 1N(t), wherein: T is the minimal sampling time interval of digital collection unit, and N is the channel number of hyperchannel reference channel;
The reference analog signal of c, hyperchannel reference channel different delayed time time and the analogue echoes signal of receive channel carries out analog to digital conversion by the high-speed figure collecting unit and binary coding is converted into digital signal, be designated as respectively x 11(n), x 12(n) ... x 1Nand x (n) 2(n);
D, by the echo digital signal x collected 2and hyperchannel reference digital signal x (n) 11(n), x 12(n) ... x 1N(n) carry out respectively the simple crosscorrelation time delay and estimate computing, obtain time delay estimated value: τ 1, τ 2... τ n;
E, by the different delay estimated value obtained increase respectively 0, obtain N the measured value of laser flying time, discrete N laser flying time measured value carried out to the matched curve that linear polynomial matching correction can obtain the laser flying time, by matched curve, can be obtained, point on the corresponding curve of first measured value horizontal ordinate is the optimum delay estimated value, and the error between itself and actual value will be much smaller than the error between single simple crosscorrelation time delay estimated value and actual value.
Compared with prior art, its remarkable advantage is in the present invention: (1) device is simple, workable; (2) traditional analog method adopt simulation constantly to differentiate to be subject to noise and such environmental effects large, simulation timing chip temperature influence timing error is large, the present invention adopts digitized measuring method to be subject to noise, temperature, such environmental effects little; (3) the laser flying time resolution is better than the digital measuring system of identical acquisition rate, compares the digital measuring system that is all the 200M sample frequency, and its measured value precision is increased to 20 times.
Below in conjunction with accompanying drawing, the invention will be further described.
The accompanying drawing explanation
Fig. 1 is the structural representation that the present invention is based on the laser flying time measurement device of hyperchannel time delay estimation.
Fig. 2 the present invention is based on the digital collection unit of the laser flying time measurement device that the hyperchannel time delay estimates and the structural representation of digital signal processing unit.
Fig. 3 is the structural representation that the present invention is based on the hyperchannel reference channel delay unit of the laser flying time measurement device that the hyperchannel time delay estimates.
Fig. 4 the present invention is based on the hyperchannel reference analog signal of the laser flying Method Of Time Measurement that the hyperchannel time delay estimates and the position view of analogue echoes signal.
Fig. 5 is the echo digital signal samples figure that the present invention is based on the laser flying Method Of Time Measurement of hyperchannel time delay estimation.
Fig. 6 is the relevant Time Delay Estimation Algorithms realization flow figure that the present invention is based on the laser flying Method Of Time Measurement of hyperchannel time delay estimation.
Fig. 7 is that the relevant time delay that the present invention is based on the laser flying Method Of Time Measurement of hyperchannel time delay estimation estimates, at signal, the schematic diagram under noise-free case is arranged.
Fig. 8 is the measured value linear polynomial fitted figure that the present invention is based on the laser flying Method Of Time Measurement of hyperchannel time delay estimation.
Embodiment
In conjunction with Fig. 1, the present invention is based on the laser flying time measurement device that the hyperchannel time delay is estimated, comprise optical system and electronic system two parts.Wherein optical system consists of transmitting optics, reception optics, the first level crossing 1 and the second level crossing 2; Electronic system consists of generating laser, receive channel, hyperchannel reference channel, digital collection unit and digital signal processing unit.The first level crossing 1 is identical with the optical parametric of the second level crossing 2, as transmissivity 90-98%, reflectivity 0.5-1%.Before the first level crossing 1 is placed in generating laser, its centre distance generating laser 3-5mm, with generating laser angle at 45 °, before the second level crossing 2 is placed in the hyperchannel reference channel, its centre distance hyperchannel reference channel 3-5mm, with hyperchannel reference channel angle at 45 °, 2 one-tenth 90 ° of angles of the first level crossing 1 and the second level crossing.Before transmitting optics is placed in the first level crossing 1, apart from generating laser 88mm, before reception optics is placed in receive channel, apart from receive channel 88mm, transmitting optics and reception optics parallel.The generating laser Emission Lasers, one road first sees through the first level crossing 1, then through transmitting optics, collimate, arrive receive channel through receiving optical convergence after being reflected by target, another Lu Xianjing first level crossing 1 reflects, by the second level crossing 2 reflections, enters the hyperchannel reference channel, and receive channel all is connected with the digital collection unit with the hyperchannel reference channel.Digital collection unit one end is connected with the hyperchannel reference channel with receive channel, the reference analog signal of the analogue echoes signal of receive channel and hyperchannel reference channel is carried out to analog to digital conversion binary coding, the other end is connected with digital signal processing unit, and the echo digital signal and the hyperchannel reference digital signal that collect are sent into to digital processing element.Digital signal processing unit carries out the line linearity fitting of a polynomial correction of estimating to go forward side by side of simple crosscorrelation time delay by the echo digital signal that receives and hyperchannel reference digital signal and tries to achieve the optimum delay estimated value.
In conjunction with Fig. 2, the digital collection unit that the present invention is based on the laser flying time measurement device of hyperchannel time delay estimation comprises ADC acquisition module and acquisition control module two parts: the ADC acquisition module is used six ADC chips to realize, five for gathering the hyperchannel reference analog signal, and a slice is for gathering the analogue echoes signal; Acquisition control module is integrated in a slice FPGA, for generation of ADC control signal and clock signal.Digital signal processing unit comprises the data buffering module, data processing module, and data memory module three parts: data buffering module and acquisition control module are integrated in same a slice FPGA, will send into data processing module after data buffering; Data processing module is integrated in a slice dsp chip, the hyperchannel reference digital signal that the data buffering module is sent into and echo digital signal are carried out respectively the estimation of simple crosscorrelation time delay, then the different delay estimated value obtained are carried out to linear polynomial matching correction and try to achieve the optimum delay estimated value; The data that data memory module obtains for temporary transient storage data processing module, be connected with digital signal processing module by data bus, by two SDRAM, realized.ADC chip, FPGA, dsp chip can be by commercial acquisition.
In conjunction with Fig. 3, the present invention is based on the formation of the hyperchannel reference channel of the laser flying time measurement device that the hyperchannel time delay estimates: the hyperchannel reference channel mainly comprises with reference to receiving element and delay unit, delay unit consists of N-1 time delay subelement, and the delay time of each subelement is by the LC filtering circuit, realize.The laser signal that will reflect through first and second level crossing 1,2 with reference to receiving element is converted to reference electrical signal, delay unit to reference electrical signal carry out respectively 0, time delay, form N hyperchannel reference signal comprising former reference electrical signal, form the hyperchannel reference channel, wherein: T is the minimum sampling interval of high-speed figure collecting unit, the channel number that N is the hyperchannel reference channel.
The present invention is based on the laser flying Method Of Time Measurement that the hyperchannel time delay is estimated, step is as follows:
A, receive channel and hyperchannel reference channel are placed according to aforesaid spatial relationship, in the moment of Laser emission, opened receive channel and hyperchannel reference channel simultaneously, reference analog signal and analogue echoes signal that two channels receive are designated as respectively x 1and x (t) 2(t).
B, in conjunction with Fig. 4, the delay unit of hyperchannel reference channel inside to reference analog signal carry out respectively 0, time delay, form N hyperchannel reference signal comprising former reference analog signal, be designated as respectively x 11(t), x 12(t) ... x 1N(t), wherein: T is the minimal sampling time interval of high-speed figure collecting unit, N is the number of channel of hyperchannel reference channel, when the sample frequency of sample circuit is 200MHz, corresponding minimal sampling time is spaced apart 5ns, get N=5, the number of channel of hyperchannel reference channel is 5, and the delay time of adjacent reference channel differs 1ns.
The reference analog signal of c, hyperchannel reference channel different delayed time time and the analogue echoes signal of receive channel carries out analog to digital conversion by the digital collection unit and binary coding is converted into digital signal, be designated as respectively x 11(n), x 12(n) ... x 1Nand x (n) 2(n).
In conjunction with Fig. 5, the discrete echo digital signal that the analogue echoes signal obtains through high-speed sampling, due to sample rate 200M only, the echo-pulse that is 100ns for a pulsewidth can only obtain at most 20 discrete points.
D, by the echo digital signal x collected 2and hyperchannel reference digital signal x (n) 11(n), x 12(n) ... x 1N(n) carry out respectively the simple crosscorrelation time delay and estimate computing, obtain time delay estimated value: τ 1, τ 2... τ n.
In conjunction with Fig. 6, the implementation procedure of relevant time delay estimation at digital signal processing unit is described.Wherein the related function of a road reference digital signal and echo digital signal is:
R 12 ( m ) = 1 N Σ n = 0 N x 1 ( n - m ) x 2 ( n )
= 1 N x 1 ( - n ) x 2 ( n )
Then above formula is carried out to Fast Fourier Transform (FFT),
F [ R 12 ( m ) ] = F [ 1 N x 1 ( - n ) x 2 ( n ) ] = 1 N X 1 * ( ω ) X 2 ( ω )
Finally its result is done to inverse fast Fourier transform and can obtain cross correlation function.
Wherein, relevant time delay estimation is the basic skills of the time domain similarity degree of two signals of comparison.The discrete-time signal model of hypothetical reference channel and receive channel is:
x 1 ( n ) = s ( n - τ 1 ) + n 1 ( n ) x 2 ( n ) = a · s ( b · n - τ 2 ) + n 2 ( n ) - - - ( 1 )
In formula: x 1(n) be reference digital signal, x 2(n) be the echo digital signal, s (n) is the source signal of return laser beam, and n is sampling number, and a is the decay factor of echoed signal, and b is the broadening factor of echoed signal, τ 1, τ 2respectively the laser flying time that LASER Light Source arrives reference channel and receive channel, τ=τ 21the time delay of receive channel with respect to reference channel, n 1and n (n) 2(n) be respectively the noise signal of two channels, s (n), n 1and n (n) 2(n) two pairwise uncorrelateds.
Reference signal x 1and echoed signal x (n) 2(n) related function R 12(τ) can be expressed as:
R 12(τ)=E[x 1(n)x 2(n-τ)]??????????????????(2)
By (1) formula substitution (2) formula:
R 12(τ)=E[a·s(n-τ 1)s(b·n-τ 2)]+E[s(n-τ 1)n 2(n)]
+E[a·s(b·n-τ 2)n 1(n)]+E[n 1(n)n 2(n)]
Due to s (n), n 1and n (n) 2(n) two pairwise uncorrelateds, so above formula can become:
R 12(τ)=E[a·s(n-τ 1)s(b·n-τ 2)]??????????(3)
Because decay factor a and the broadening factor b of echoed signal do not affect related function, so above formula can be changed to:
R 12(τ)=E[s(n-τ 1)s(n-τ 2)]=R rr[τ-(τ 21)]????????(4)
According to related function character,
R rr[τ-(τ 21)]≤R rr(0)
As τ=τ 21the time, R rr[τ-(τ 21)] reach maximal value.The time delay estimated value can be obtained by formula (4), selects the peak point of related function as the time delay estimated value.
τ=arg{max[R rr(τ-(τ 21))]}????????????????????????(5)
In formula, arg () means to get function argument, and max () means to ask the function maximal value.
Echo time delay τ can be calculated by following formula:
τ=m·T+τ s???????????????????????????????????????????(6)
In formula, T is sampling time interval, and m is sampling number, τ sfor system delay.From formula (5), (6), the precision that time delay is estimated is directly determined by the time interval and the related function of digital collection.
The precision of estimating in order to improve time delay, the most direct method is to improve the sample rate of ADC, but realizes more difficult.Therefore, on the basis of estimating in relevant time delay, carried out the multichannel delay process with reference to channel and formed the hyperchannel reference channel.The hyperchannel reference signal means as follows:
x 11 = s ( n - τ 1 ) + n 11 ( n ) x 12 = s ( n - τ 1 - 1 N T ) + n 12 ( n ) · · · · · · x 1 N = s ( n - τ 1 - N - 1 N T ) + n 1 N ( n ) - - - ( 7 )
In formula: x 11, x 12and x 1Nthe reference signal of difference hyperchannel reference channel first via channel, the second path channels, N path channels, n 11(n), n 12and n (n) 1N(n) noise signal of difference hyperchannel reference channel first via channel, the second path channels, N path channels, s (n) is the source signal of return laser beam, n is sampling number, τ 1be the laser flying time that LASER Light Source arrives reference channel, N is the channel number of many reference channels, and T is the minimal sampling time interval of digital collection system.
The relevant time delay estimated value τ of echoed signal and k road reference signal kcan be expressed as:
τ k = τ 2 - τ 1 - k - 1 N T , k = 1,2 · · · N - - - ( 8 )
N road reference signal and echoed signal are done to computing cross-correlation, and the resolution that time delay can be estimated rises to T/N by T.The relevant time delay estimated value τ of echoed signal and k road reference signal kcan be expressed as again:
τ k = ( m - k - 1 N ) T + τ s , k = 1,2 · · · N - - - ( 9 )
Ideally, the difference between the time delay estimated value that echoed signal and adjacent reference signal computing cross-correlation obtain is but because the digital sample minimum interval is greater than this difference, so actual measured results has deviation certainly.
Echoed signal and N road reference signal computing cross-correlation obtain N time delay estimated value, are designated as respectively: τ 1, τ 2τ n, by N time delay estimated value increase respectively 0, obtain N the measured value of laser flying time.General expression is:
d k = τ k + k - 1 N T , k = 1,2 · · · N - - - ( 10 )
In formula: d kfor k the measured value of laser flying time, τ kfor the time delay estimated value of echoed signal and k road reference signal, N is the channel number of many reference channels, and T is the minimal sampling time interval of digital collection system.
Discrete N laser flying time measured value carried out to the matched curve that the linear polynomial matching can obtain the laser flying time.Can realize that by the linear polynomial matching measured value, to the approaching of actual value, further reduces the time measurement error.By matched curve, can be obtained, the point on the corresponding curve of first measured value horizontal ordinate is the time delay estimated value of laser flying time, and the error between itself and actual value will be much smaller than the error between single simple crosscorrelation time delay estimated value and actual value.
In conjunction with Fig. 7, (a) be the noiseless reference signal, (b) for noise reference signal is arranged, (c) receive signal for noiseless, (d), for there being noise to receive signal, be (e) that noiseless simple crosscorrelation time delay is estimated, (f) for there being noise simple crosscorrelation time delay to estimate.Illustrate that relevant time delay estimation has under muting situation and all is suitable at signal, when signal has noise, correlation intensity can be subject to the impact of noise, but the characteristic of the corresponding time delay estimated value of the peak value of correlation intensity curve is unaffected.
E, by the different delay estimated value τ obtained 1, τ 2... τ nincrease respectively 0, obtain N the measured value of laser flying time.Discrete N laser flying time measured value carried out to the matched curve that the linear polynomial matching can obtain the laser flying time.Can realize that by linear polynomial matching correction measured value, to the approaching of actual value, further reduces the time measurement error.By matched curve, can be obtained, the point on the corresponding curve of first measured value horizontal ordinate is the optimum delay estimated value, and the error between itself and actual value will be much smaller than the error between single simple crosscorrelation time delay estimated value and actual value.
In conjunction with Fig. 8, the laser flying time that is 401ns for an actual value, the reference signal of the echoed signal of receive channel and hyperchannel reference channel time delay respectively estimates that 5 measured values that obtain are respectively: 400ns, 401ns, 402ns, 403ns, 400ns.These 5 measured values are carried out to the linear polynomial matching, and trying to achieve the value that first measured value 400ns is corresponding on curve is 400.75ns, with the absolute error of actual value be only 0.25ns.And adopting the measuring system that is all the 200M sample frequency, its measurement error minimum is 5ns.This method precision is increased to 20 times.
In digital collection unit picking rate, under constant condition, the number of channel that increases reference channel can further improve the precision of laser flying time measurement.When being on the other hand, the number of channel that increases reference channel has also increased the complexity of digital collection unit.The different laser flying time measurement for accuracy requirement, select suitable reference channel number to be necessary.

Claims (4)

1. a laser flying time measurement device of estimating based on the hyperchannel time delay, it is characterized in that comprising optical system and electronic system two parts, wherein optical system is by transmitting optics, receive optics, the first level crossing [1] and the second level crossing [2] form, electronic system is by generating laser, receive channel, the hyperchannel reference channel, digital collection unit and digital signal processing unit form, the first level crossing [1] is identical with the optical parametric of the second level crossing [2], before the first level crossing [1] is placed in generating laser, with generating laser angle at 45 °, before the second level crossing [2] is placed in the hyperchannel reference channel, with hyperchannel reference channel angle at 45 °, the first level crossing [1] becomes 90 ° of angles with the second level crossing [2], transmitting optics is placed in the first level crossing [1] before, and before reception optics is placed in receive channel, transmitting optics and reception optics parallel, the generating laser Emission Lasers, one road first sees through the first level crossing [1], then through transmitting optics, collimate, arrive receive channel through receiving optical convergence after being reflected by target, another Lu Xianjing the first level crossing [1] reflection, enter the hyperchannel reference channel by the second level crossing [2] reflection, receive channel all is connected with the digital collection unit with the hyperchannel reference channel, this digital collection unit one end is connected with the hyperchannel reference channel with receive channel, the reference analog signal of the analogue echoes signal of receive channel and hyperchannel reference channel is carried out to analog to digital conversion binary coding, the other end is connected with digital signal processing unit, the echo digital signal and the hyperchannel reference digital signal that collect are sent into to digital signal processing unit, digital signal processing unit carries out the line linearity fitting of a polynomial correction of estimating to go forward side by side of simple crosscorrelation time delay by the echo digital signal that receives and hyperchannel reference digital signal and tries to achieve the optimum delay estimated value, wherein, the formation of hyperchannel reference channel: the hyperchannel reference channel comprises with reference to receiving element and delay unit, and delay unit consists of N-1 time delay subelement, and the delay time of each subelement is by the LC filtering circuit, realize, with reference to receiving element will through the first level crossing, [laser signal that little the second level crossing [2] reflects be converted to reference electrical signal, and delay unit carries out respectively reference electrical signal time delay, form N hyperchannel reference signal comprising former reference electrical signal, form the hyperchannel reference channel, wherein: T is the minimum sampling interval of high-speed figure collecting unit.
2. the laser flying time measurement device of estimating based on the hyperchannel time delay according to claim 1, it is characterized in that the digital collection unit comprises ADC acquisition module and acquisition control module two parts, the ADC acquisition module is used six ADC chips to realize, five for gathering the hyperchannel reference analog signal, and a slice is for gathering the analogue echoes signal; Acquisition control module is integrated in a slice FPGA, for generation of ADC control signal and clock signal.
3. the laser flying time measurement device of estimating based on the hyperchannel time delay according to claim 2, it is characterized in that digital signal processing unit comprises the data buffering module, data processing module, data memory module three parts, data buffering module and acquisition control module are integrated in same a slice FPGA, data processing module will be sent into after data buffering, this data processing module is integrated in a slice dsp chip, the hyperchannel reference digital signal that the data buffering module is sent into and echo digital signal are carried out respectively the estimation of simple crosscorrelation time delay, then the different delay estimated value obtained is carried out to linear polynomial matching correction and try to achieve the optimum delay estimated value, the data that data memory module obtains for temporary transient storage data processing module, be connected with data processing module by data bus, by two SDRAM, realized.
4. a measuring method of utilizing the described laser flying time measurement device of estimating based on the hyperchannel time delay of claim 1 to 3 any one is characterized in that comprising the following steps:
A, in the moment of Laser emission, open two channels, reference analog signal and analogue echoes signal that two channels receive are designated as respectively x simultaneously 1and x (t) 2(t);
The delay unit of b, hyperchannel reference channel inside carries out respectively reference analog signal time delay, form N hyperchannel reference signal comprising former reference analog signal, be designated as respectively x 11(t), x 12(t) ... x 1N(t), wherein: T is the minimal sampling time interval of digital collection unit, and N is the channel number of hyperchannel reference channel;
The reference analog signal of c, hyperchannel reference channel different delayed time time and the analogue echoes signal of receive channel carries out analog to digital conversion by the high-speed figure collecting unit and binary coding is converted into digital signal, be designated as respectively x 11(n), x 12(n) ... x 1Nand x (n) 2(n);
D, by the echo digital signal x collected 2and hyperchannel reference digital signal x (n) 11(n), x 12(n) ... x 1N(n) carry out respectively the simple crosscorrelation time delay and estimate computing, obtain time delay estimated value: τ 1, τ 2... τ n;
E, the different delay estimated value obtained is increased respectively obtain N the measured value of laser flying time, discrete N laser flying time measured value carried out to the matched curve that linear polynomial matching correction can obtain the laser flying time, by matched curve, can be obtained, point on the corresponding curve of first measured value horizontal ordinate is the optimum delay estimated value, and the error between itself and actual value will be much smaller than the error between single simple crosscorrelation time delay estimated value and actual value.
CN 201110042431 2011-02-22 2011-02-22 Laser time-of-flight measurement device based on multi-channel time delay estimation and method thereof Expired - Fee Related CN102176004B (en)

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